Dam construction is built to withstand the rate of water into the reservoir, lake or recreation areas. Often dams are also used to provide water to a hydroelectric plants. Most of the dam also has a section called the floodgates to dispose of unwanted water gradually or sustainable. The check dam or dam is building to withstand the water flow rate and water level or increase.
Usually the dam functioned for agricultural irrigation, power generation, recreation and fisheries. Dams were built in Java because the area is mountainous, frequent flooding, extensive agricultural areas and others. Average reservoir is a large pool used to collect water and used for various purposes. This reservoir is nothing natural or artificial. In West Java dams in small numbers quite a lot and the people of West Java called reservoirs relatively small size such as Situ.
Dam (dam) and dam (weir) is actually a different structure. Dam (weir) is a low head dam structure (lowhead dam), which serves to raise the water level, usually found in the river. Increased surface river water will melimpas through peak / mercu weir (overflow). Can be used as a measure of the speed of water flow in the canal / river and could be a driving force in the traditional pengilingan European countries.
In countries with sizeable rivers and torrential flow, a series of dams can be operated to form a water transport system. In Indonesia, many dams used for irrigation by raising the water level, when the river water level is lower than the face of the land that will be watered.
Figure 27. a large dam on the river